热处理对Mg-5Gd-0.5Sc-Mn合金组织与力学性能的影响

Effect of heat treatment on microstructure and tensile property of Mg-5Gd-0. 5Sc-Mn alloy

利用光学显微镜、扫描电镜及力学性能测试等分析手段研究了不同热处理条件对Mg-5Gd-0.5Sc-Mn合金的微观组织和力学性能的影响。结果表明,Mg-5Gd-0.5Sc-Mn合金具有良好的室温性能及高温稳定性。比较T5和T6两种热处理工艺发现:挤压态合金在200℃经过不同时间的时效,T5态较T6态的峰值时效硬度高,且T5态到达峰值时效的时间比T6态的短;合金T5态的室温抗拉强度可以达到216MPa,200℃达到191MPa,均高于T6态的191和186MPa;T5态室温及高温条件下的断裂模式表现为准解理及微孔聚集的塑性断裂,而T6态室温及高温条件下分别为解理和准解理的脆性断裂。

Effect of heat treatment on microstructure and tensile property of Mg-5Gd-0.5Sc-Mn alloy was studied by means of OM,SEM and tensile test.The results show that the alloy exhibits a favorable tensile properties at room temperature and thermal stability,after aging at 200 ℃ for different time,the hardness of the extruded alloy plus T5 temper （named alloy-T5） was higher than that of extruded alloy plus T6 temper,and the time to peak aging hardness of alloy-T5 is shorter than that of alloy-T6.The tensile strength of alloy-T5 is 216 MPa at room temperature and 191 MPa at 200 ℃ ,which is higher than that of alloy-T6.The fracture mode of alloy-T5 is quasi-cleavage fracture at room temperature and microvoid coalescence fracture at 200 ℃ .However,the alloy-T6 exhibits brittle fracture at room temperature and quasi-cleavage fracture at 200 ℃ 。